Goblet cell metaplasia in the pulmonary alveolar epithelium in a rat.

Spontaneous goblet cell metaplasia in the pulmonary alveolar epithelium in a 110-wk-old male Jcl:Wistar rat is described. The rat had a dark red spherical mass in the center of the left lobe of the lung. The mass consisted of distended alveoli and bronchioles filled with mucus and nonciliated epithelial cells with numerous goblet cells lining the alveoli on the periphery of the mass. The goblet cells produced Alcian blue- and high iron diamine-positive sulfated glycoprotein differing from the sialylated glycoprotein seen in the normal rat airway surface epithelium. To the best of this investigator's knowledge, this is the first report dealing with detailed morphological and histochemical features of goblet cell metaplasia in the pulmonary alveolar epithelium resulting in mass formation due to mucous production.